Integration circuits (ICs) or chips designed using, for example, a very-large-scale integration (VLSI) process, typically draw power from external sources such as grid power (mains), batteries, or the like. Increasingly, however, devices utilizing such components demand greater levels of energy efficiency. This is largely due to the prevalence of wireless and mobile devices becoming more widespread.
Personal communication devices, such as mobile phones, smart phones, PDAs, handheld PCs, and the like, as well as many entertainment devices, such as media players, MP3, MP4, mobile DVD, digital cameras, and the like, as well as other household, office and leisure gadgets are commonly powered by batteries of electrochemical power cells. A drawback with battery-operated devices is that electrochemical power cells often run out of power at inconvenient times and therefore batteries need to be regularly recharged or replaced.
Such devices may be less dependent upon power provided by electrochemical power cells if some of their components were able to power themselves. Thus, the energy efficiency of mobile devices may be improved by a convenient and effective solar powered VLSI chip.
Furthermore, such solar powered components could be effectively used in applications where a power supply is unavailable. Self-powering components may therefore be utilized in a variety of stand-alone communication units, road signs for remote locations, in buoys, floats or other maritime applications.
Attempts have been made to connect VLSI chips to elements, such as photovoltaic cells (PVs), in order that they might draw solar power therefrom, and therefore the chips and photovoltaic cells are generally manufactured separately and later connected together using external wiring, gates, contacts or terminals.
For example, U.S. Pat. No. 6,680,468 to Wang, entitled, “Electrical-supply-free MOS integrated circuit”, describes an electrical-supply-free MOS integrated circuit comprising: a semiconductor device having a current terminal, an input voltage terminal, and a common terminal. The voltage difference between the input voltage terminal, and the common terminal, controls current flow through the current terminal. An opto-electronic device is also provided to convert incident light into an electrical signal. In another example, PCT Application Publication No. WO/2003/079438 to Jaussaud, et al. entitled, “Multijunction Photovoltaic Device with Shadow-free Independent Cells and the Production Method Thereof”, describes a multijunction photovoltaic device with independent cells. Contact pick-ups are provided on the front and/or rear face of the cells by means of metal wells, the sides of which are insulated from the semi-conducting layers.
Furthermore, US Patent Application Publication No. 2002/0170591 to Armer, et al., entitled “Method and apparatus for powering circuitry with on-chip solar cells within a common substrate”, describes a light-powered transponder. In order to create sufficient voltage differential, two photovoltaic elements are used. The photovoltaic elements generate voltages of different polarities. Despite the inherent difficulties presented by the use of a standard Complementary metal-oxide-semiconductor (CMOS) process, Armer's system is directed towards achieving a voltage differential sufficient to power an ASIC by using photovoltaic elements independently to generate voltages with different polarities.
As mentioned all the above-described solutions require separate interconnecting conductors between their integrated circuits and their power sources. However, any additional components compromise the dimensions of the host devices and may also provide additional sources of failure.
FIG. 1 shows a schematic block diagram representing a conventional arrangement of a solar powered integrated circuit 100. It is noted that in order to use solar energy, devices are typically designed to include three separate components: an integrated circuit 104; a photovoltaic cell 102; and a connecting interface 103.
The integrated circuit (IC) 104 may be a miniaturized electronic circuit typically including semiconductor devices as well as passive components. ICs are generally manufactured upon the surface of a thin substrate of semiconductor material. Variously, integrated circuits 104 may be based upon, but not limited to, complementary metal-oxide-semiconductor (CMOS) chips, a micro-electro-mechanical systems (MEMS) chip, a very large scale integration (VLSI), or the like.
The photovoltaic cell 102 is configured to convert light into electricity typically using the photovoltaic effect. As the photovoltaic cell 102 is typically manufactured separately from the IC, it is necessary to provide the connecting interface 103.
The connecting interface 103 provides a conductive pathway, such as external wiring, gates, contacts, terminals, and the like, between the photovoltaic cell 102 and the integrated circuit 104. In addition, the connecting interface 103 may provide an intermediate external source layer of a power supply, such as an electrochemical cell, a capacitor or the like.